Machine for sealing receptacles



38 mEXHAUSTPl/MP I By J- BJJ TTLE ATTORNEY HC. HARRISON J03 INVENTOQSFiled June 15 1940 Iii/10h i H C HARRISON ET AL MACHINE FOR SEALINGRECEPTACLES Aug. 10, 1943.

F/GZ

T0 HYDROGEN CYLINDER Patented Aug. 10,1943

UNITED STATES PATENT OFFICE MACHINE roR SEALING RECEPTACLES.

Henry 0. Harrison, Port Washington, and John B.

Little, New York; N. Y., assignors to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation of New York ApplicationJune15, 1940, Serial No. 340,655

6 Claims.

This invention relates to the art of sealing hollow metallic receptaclesand more particularly to an improved machine for use in this art.

Although not limited thereto, the invention has special utility in themanufacture of electric switches of the liquid contact type. A switch ofthis type, which the machine according to the invention has beenparticularly adapted to seal, comprises a bottom can member having theupper rim of its side wall turned outwardly to form a flange, an uppereyelet portion having its upper end-sealed by a glass insulator throughwhich one switch terminal extends and having its lower rim turnedoutwardly to form a flange which may be Welded to the flange of the canmember, a

body of mercury in the bottom of the can mem-' her and a hollowcylindrical armature floated upon the surface of the mercury throughwhich the switch terminal extends. A second terminal may be soldered tothe bottom can member. If the armature is subjected to an electricfield, and pulled downwardly toward the mercury pool, the mercurybecomes displaced upwardly through the hollow armature into engagementwith the terminal depending from the upper eyelet portion wherebycontact is established between the terminals through the mercury pool.It is generally found desirable to provide an operating atmosphere of areducin as, such as hydrogen, which may be introduced into the switchbefore it is sealed.

It is an object of the present invention to provide an improved weldingassembly whereby the two portions of a switch receptacle may be enclosed in a chamber thereof which can be evacuated, through which ameasured amount of mercury can be deposited in one portion of the switchreceptacle, which can then be filled-to a desired pressure with agas-and in which the portions of the switch receptacle can be weldedtogether.

It is a further object of the invention to provide an apparatus forsealing metallic receptacles in an efficient and. simple manner.

In accordance with the present invention these objects are attained bythe provision of a welding assembly insertable into a welding press. Theassembly has a base member from the center of which a lowerweldingelectrode extends upward- 15?, which electrode is provided with an axialsocket in which the lower can portion of a switch receptacle of the typehereinbefore described may be supported with it flanged rim resting uponthe upper end of the electrode. Attachable to the piston or pressuremember of the press is an upper welding-electrode support from thecenter of which a second electrode depends'which electrode has a sockettherein for receiving the upper or eyelet portion of a receptacle withits flanged rim engaged against the lower end of the electrode. Securedto the base member and surrounding both electrodes is a piece of thickwalled rubber tubing which with the base member and upper electrodesupporting member form a chamber within which the electrodes areenclosed. This chamber may be connected by a valved pipe with a suitableexhaust pump. Also supported within the chamber is a flexible tube havinits upper end bent over and normally positioned above the socket in thelower electrode. This tube is connected to a mercury supply and to aflask of gas, for example, hydrogen, under ressure.

In using the assembly, the eyelet portion of the receptacle is placed inthe socket of the upper electrode, the can portion with the armatureplaced therein is positioned in the socket of the lower electrode andthe upper electrode is then lowered into the upper end of the rubbertubing, but not low enough to deflect the flexible tube. The valve tothe hydrogen flask and the measuring valve to the mercury supply arethen closed and the valve to the exhaust pump is opened to exhaust thechamber in which the portions of the receptacle are enclosed. When theexhaustion has been completed, the measuring valve to the mercury supplyis turned to deposit a measured quantityof mercury in the lower portionof the flexible tube. The measuring valve is then closed and the valveto the hydrogen flask is opened thereby forcing the measured quantity ofmercury through the flexible tube into the can portion of thereceptacle. The exhaust pump pulls the hydrogen into the chamber therebypurging it. The valve to the exhaust pump is then closed and hydrogen ispermitted to flow into the, chamber until the requisite hydrogenpressure is established after which the valve to the hydrogen supply isclosed. The upper electrode is then lowered to force the flanges of theportions of the receptacle together, the lowering of th electrodepressing the flexible tube to one side. The welding current is thenapplied to the electrodes whereby theflanges of the portions of thereceptacle are welded together.

Having briefly described the welding assembly and the manner in which itis to be used, referonce may now be had for a more comprehensiveunderstanding of the invention to the followin detailed description readin connection with the accompanying drawing in which:'

Fig. 1 shows partially in cross-section, the welding assembly inaccordance with the present invention;

Fig. 2 is an enlarged cross-sectional view of the per and lower portionsof a switch element of the type which the assembly of Fig.1 isparticulariy adapted to manufacture; and

Fig. 3 is an enlarged cross-sectional view of a completely assembledswitch element.

Referring first to Figs. 2 and 3, the switch elementdisclosed therein isof the general type disclosed in Patent No. 2,259,661, granted October21, 1941 to C. E. Pollard. It comprises a bottom can portion I havingits upper edge turned outwardly to form a flange 2 which is providedwith a circular ridge 3 for affording a better welding surface. The camportion is preferably pressed from nonmagnetic stainless steel stock.The upper portion 4. is produced in the form of an eyelet having a loweroutturned flange 5 which may be welded as hereinafter described to theflange 2 of the can portion I. The eyelet portion is pressed from metalalloy stock which may be readily sealed to glass. When completelyassembled as disclosed in Fig. 3, the upper eyelet portion 4 has itsupper end sealed by a glass bead 3 through the center of which an upperelectrode or terminal I extends, a small pool of mercury 9 is depositedin the bottom of the lower can portion 1 upon which a hollow cylindricaliron armature 9 floats, and the depending end of the terminal I extendsthrough the hollow armature to a point just above the upper surface ofthe mercury pool. Before the portions of the switch receptacle arewelded together, they are evacuated and refilled with hydrogen underpressure as will be hereinafter described. After the welding operationhas been completed, the lower terminal I is soldered to the bottom ofthe can portion I. a

A switch element of the type just described is assembled in alignedholes in the polar extention I4 for the purpose to be later describedand with an axial threaded hole I5 into which is threaded the shank I3of a lower electrode I'I.

7 To seat the electrode firmly on the base member so that the pressureapplied thereto in the operation of the press will not be borne by thethreads of the member I3 and of the shank I9, the shank I3 is screwedinto the axial hole I5 until the shoulder I8 of the electrode is seatedfirmly on the surface I4 of the base member [3. The electrode I1 isprovided with an axial hole into which a cylindrical adapter I9 isthreaded. The adapter is provided with an axial socket 20 of suflicientdepth and diameter to receive the lower can porsions of a relay core insuch a position that when flux-is generated in the magnetic circuitincluding the polar extensions and the armature 9, the armature willtend to center itself between the polar extensions and will therefore bedrawn downwardly into the bottom portion I of the switch element,thereby displacing mercury upwardly into engagement with the end oftermi nal 1 whereby a conducting path is established between theterminals I and I0 through the mercury. The can portion I being ofnon-magnetic stainless steel does not become magnetized to impede themovement of the armature 9. When flux ceases to flow through thearmature, the surface tension of the mercury pool restores the armatureto its normal positionand the mercury breaks contact with the terminalI.

To weld the bottom can portion I and the upper eyelet portion 4 of aswitch element together and to insure that before the portions arewelded they are evacuated and refilled with hydrogen, the welding pressassembly disclosed in Fig. 1 has been devised. The assembly is arrangedfor insertionin the usual type of welding press which has a lower fixedelectrode support II and an upper movable electrode support I2 which maybe secured to the pressure member of the press.

The assembly is provided with a circular base member I3 whichmay besecured to the flange of tion I of the switch element such as isdisclosed in Fig. 2, the diameter of the socket 20 being such that thelower can portion I will fit quite snugly therein. The base member I3 isalso provided with a concentric groove 2I in which are secured a shortsection of metal tubing 22 and a longer 7 the hole 25 until the shoulder28 of the electrode I is seated firmly on the lower surface of themember 24. The outer cylindrical wall of the member 24 is tapered asindicated at 29 for guiding the member 24 into the upper end of therubber tubing 23 and for expanding the upper end of the tubing forsecuring a tighter flt therein. The electrode 21 is provided with anaxial hole into which a cylindrical adapter 39 is threaded. The adapteris provided with an axial socket 3I of suflicient depth and diameter toreceive the upper eyelet portion 4 of the switch element such as isdisclosed in Fig. 2, the diameter of the socket 3| being such that theeyelet portion 4 will flt quite snugly therein.

To more effectively seal the chamber 50 against the leakage which mightresult due to imperfectand 25 in the members I3 and 24, the holes I5 and25 are sealed after threading by plugs 5| and 52 brazed therein.

Extending through the base member I3 is a duct 32 in the inner end ofwhich is secured a short section of tubing 33, the upper end of whichextends above the surface of the depressed portion I4 so that anymercury which may become split in'the depressed portion I4 during theuse of the assembly cannot flow into the duct 32. Secured in the outerend of the duct 32 is a pipe 34 which is connected by a T 35 with asuitable pressure gauge 33 and through a valve 31 with a pipe 33extending to any suitable exhaust pump (not shown).

Extending upwardly through the base member I3 is a small flexible tube39, the upper end of which is bent as indicated at 49 so that its endportion or orifice overlies the socket 29 in the lower electrode adapterI9. The lower end M of the tube 39 lies in a groove in the lower face amercury reservoir 44. The stock cock spindle 45 of the stop cock 43 isprovided with a pocket 45 of a size to hold just the correct quantity ofmercury for deposit in a single switch ele ment. The tube 42 is alsoconnected by a glass stop cock 41 to a pipe 48 connected with a flask orcylinder of hydrogen (not shown). The utility of the welding assemblyabove described may be best understood by considering its application tothe manufacture of a switch element of the type disclosed in Fig. 3. Tostart the welding of the parts of the switch element together, theplunger of the welding press is raised until the member 24 is entirelyremoved from the upper end of the rubber tubing 23, thus giving freeaccess to both of the weldingelectrodes. An assembled eyelet portion ofa switch element including the eyelet 4, glass bead 8 and terminal 1 isthen inserted into the socket 3| of the upper electrode adapter 30 untilthe flange 5 thereof rests against the lower end of such adapter and acan portion l with an armature 9 therein is then inserted into thesocket 20 in the lower electrode adapter l9 until its flange 2 restsagainst the upper end of such adapter. The upper electrode supportingmember 24 is then lowered into the upper end of the rubber tubing 23 tothe position illustrated in Fig. 1, thus closing, the upper end of thetubing and forming a closed chamber 50, the electrode supports [3 and 24forming the ends of such chamber and the rubber tubing 23 forming thecylindrical wall of such chamber. The electrodes l1 and 21 and theswitch element portion carried thereby are thus enclosed in the chamber50.

The stop cocks 45 and 41 are now closed and the valve 31 is opened,whereby the chamber is connected to the exhaust pump. Suction from suchpump now applied to the chamber 50 reduces the air pressure in thechamber whereby atmospheric pressure on the outside of the rubber tubing23 effectively seals the chamber. When the chamber and consequently theportions of the switch element disposed therein have been exhausted, thestop cock spindle 45 is turned through 180 degrees thereby depositingthe globule of mercury which fills the pocket 45 thereof into the lowerportion of the tube 42. With the spindle 45 of the stop cock in thisposition, the upper end of the tube 42 is effectively closed. The stopcock 41 is now turned to connect the hydrogen cylinder with the tube 42whereupon the pressure-of the hydrogen forces the measured quantity ofmercury from the sure is reached when the stop cock 41 is closed.

The upper electrode 21 is now lowered until the flange 5 of the eyeletportion 4 engages the flange 2 of the can portion I with the requisitewelding pressure. The downward movement of the upper electrode 21 pushesthe upper bent end 40 of the flexible tube '39 to one side so that itwill not interfere with the proper engagement of the flanges of theswitch element portions. With the proper pressure applied, the weldingcircuit connected to the electrodes is closed and a weld is effectedwhich seals the portions of the switch element together with a measuredquantity of mercury and an atmosphere of hydrogen therein. The weldingcircuit is then opened and the upper electrode 21 is raised so that theswitch element may be removed from the welding assembly. The switchelement may then be. completed by soldering the lower terminal ill tothe bottom thereof.

While the invention has been disclosed as particularly adapted to themanufacture of switch elements of the type disclosed, it is to beunderstood that by changing the adapters l9 and 30 other types and'sizesof switch elements could be similarly manufactured. It is to be furtherunderstood that the step of flllingthe switch element with gas could beomitted and the welding accomplished at the time the switch element isin an evacuated condition. Under this condition the mercury could befirst forced through the tube 39 by air pressure or gas pressure anddeposited in the can portion of the switch element as previouslydescribed and the the chamber 50 then evacuated by closing both stopcocks 43 and 41 and by opening the valve 31. a

It is also to be understood that the sealing means comprising the rubbertube and conical plunger could be replaced by other elastic closures,such as fiexlbi metallic flanges with gasket edges.

What is claimed is:

1. A machine for sealing a two-part metallic receptacle comprising afixed electrode support, a first electrode secured thereto, a movableelectrode support, a second electrode secured thereto, said electrodeshaving axial sockets in which the parts of the receptacle to be sealedare insertable, a flexible tubular wall secured at one end to said fixedsupport surrounding said first electrode and having its other endnormally open, said wall forming with said supports a closed chambersurrounding said electrodes when said movable support is moved into theopen end of said wall toward said fixed support, an air pressurereducing pump, means for connectin said pump with said chamber wherebysaid chamber may be evacuated and means for moving said movable supportand said second electrode to engage the parts of said receptacle wherebythey may be welded together.

2. A machine for sealing a two-part metallic receptacle comprising afixed electrode support, a first electrode secured thereto, a movableelectrode support, a second electrode secured thereto, said electrodeshaving axial sockets in which the parts of the receptacle to be sealedare insertable, a tubular wall of thick rubber secured at one end tosaid fixed support surrounding said first electrode and having its otherend normally open, said wall forming with said supports a closed chambersurrounding said electrodes when said movable support is moved into theopen end of said wall toward said fixed support, an air pressurereducing pump, means for connectin said pump with said chamber wherebysaid chamber may be evacuated and said wall of rubber tubing sealed tosaid movable support, and means for moving said movable support and saidsecond electrode to engage the parts of said receptacle whereby they maybe welded together.

3. A machine for sealing a two-part metallic receptacle comprising afixed electrode support, a first electrode secured thereto, a movableelectrode support, a second electrode secured thereto,

said electrodes having removable adapters therein having axial socketsin which the parts of the with said chamber whereby said chamber may beevacuated and said flexible wall sealed to said movable support, andmeans for movingsaid movable support and said second electrode to engagethe parts of said receptacle whereby they may be welded together.

4. A machine for sealing a two-part metallic receptacle for a mercuryswitch comprising a fixed support, a movable support, said supportshaving axial sockets in which the parts of the receptacle to be sealedare insertable, a flexible tubular wall secured at one end to said fixedsupport and having its other end normally open, said wall forming withsaid supports a closed chamber when said movable support is moved intothe open end of said wall toward said fixed support, an air pressurereducing pump, means for connecting said pump with said chamber wherebysaid chamber may be evacuated, a flexible tube extending into saidchamber having its inner end downturned over the socket in said firstsupport through which tube a measured quantity of mercury may bedeposited in the part of said receptacle positioned in the socket or thefirst support and through which the chamber is filled with gas at adesired pressure and means for moving said movable support to engage theparts of said receptacle for sealing, the movement of said secondsupport laterally deflecting said tube whereby the parts of saidreceptacle are sealed together.

5. A machine for sealing a two-part metallic,

receptacle for a mercury switch comprising a fixed support, a movablesupport, said supports having axial sockets in which the parts of thereceptacle to be sealed are insertable, a flexible tubular wall securedat one end to said fixed support and having its other end normally open.said wall forming withsaid supports a closed chamber when said movablesupport is moved into the open end of said wall towards said fixedsupport, an air pressure reducing pump; means for connecting said pumpwith said chamber whereby said chamber may be evacuated, a flexible tubeextending into said chamber and having its inner end downturned over thesocket in said first support, means including a supply of gas underpressure for forcing a measured quantity of mercury through said tubefor deposit in the part of said receptacle positioned in the socket orsaid first support and for filling said chamber with gas at a desiredpressure, and means for moving said movable support to engage the partsof said receptacle, the movement of said second support laterallydeflecting said tube whereby the parts of said receptacle are sealedtogether enclosing said gas.

6. A machine for sealing a two-part metallic receptacle for a mercuryswitch comprising a fixed support, a movable support, said supportshaving axial sockets in which the parts of the receptacle to besealedare insertable, a flexible tubular wall secured at one end to saidfixed support and having its other end normally open, said wall formingwith said supports a closed chamber when said movable support is movedinto the open end of said wall towards said fixed support, an airpressure reducing pump, means for connecting said pump with said chamberwhereby said chamber may be evacuated, a flexible tube extending intosaid chamber and hav ing its inner end downturned over the socket insaid fixed support, a mercury reservoir, a measj uring valve forconnecting said reservoir with said tube whereby a measured quantity ofmercury may be deposited in said tube, a supply of gas under pressure,means for connecting said gas supply to said tube whereby said measuredquantity of mercury may be forced through said tube for deposit in thepart of said receptacle positioned in the socket of said first supportand said chamber filled with said gas at the desired pressure, and meansfor moving said movable support to engage the parts of said receptacle,the movement of said second support laterally deflecting said tubewhereby the parts of said receptacle may be sealed together enclosingsaid mercury and said gas.

HENRY c. HARRISON. JOHN 12.. LI'I'I'LE.

